16 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Tap any card for details
Your boiler has detected that water is not moving around your heating system as efficiently as it should be.
Your boiler's internal computer has encountered a critical error and is unable to communicate with its own internal systems to function correctly.
Your boiler's internal computer is experiencing a communication error and cannot operate, meaning you currently have no heating or hot water.
Your boiler has detected that the internal water temperature has become dangerously high and has safely shut itself down to prevent damage.
Your boiler is struggling to accurately read the temperature of the water returning from your heating system, which means it cannot heat your home efficiently.
Your boiler is having trouble communicating with the temperature sensor for your secondary heating zone, which may prevent that part of your home from heating up properly.
Your boiler is having trouble reading the water temperature in one of your heating zones, which may stop that specific area of your home from heating up correctly.
Your boiler has detected that the water temperature in one of your heating zones is higher than it should be for safe operation.
Your boiler has stopped working because the water returning from your radiators is significantly hotter than the water leaving the boiler, suggesting the water isn't flowing correctly.
Your boiler has stopped working because the water returning from your radiators is significantly hotter than the water being sent out, suggesting a blockage or a pump problem is preventing proper circulation.
Your boiler has lost water pressure and has shut down to prevent damage, meaning it simply needs to be refilled to the correct level.
Your boiler has too much water pressure inside the system, causing it to shut down for safety.
Your boiler has detected that the safety sensor for an underfloor heating circuit has tripped to prevent the floor from overheating.
Your boiler has detected a fault with the sensor that measures the temperature of the water being sent to your radiators, which means it cannot heat your home safely.
Your boiler has tried to light several times but has failed to create a flame, meaning you currently have no heating or hot water.
Your boiler thinks it sees a flame even though the gas should be turned off, so it has shut down as a safety precaution.
Not faults — these are normal operating states. Tap to expand.
Monthly cover means no unexpected bills when your boiler breaks down.
Affiliate links. We may earn a commission at no extra cost to you.
BoilerFaultCodes